1. Field of the Invention
The present invention is related to a method of managing discontinuous reception in a wireless communication system and a related wireless communication system, more particularly, to a method of managing discontinuous reception in a wireless communication system and a related wireless communication system for enhancing power saving while reducing the likelihood of network signaling being missed or delayed.
2. Description of the Prior Art
A communication device, such as a wireless transmit/receive unit (WTRU), may communicate with a remote device via a communication system. The WTRU may be configured to perform machine-to-machine (M2M) or machine-type communications (MTC), which are communications that may be performed without human interaction. MTC WTRUs may operate in a time controlled mode, wherein an MTC WTRU attaches to a network at specified intervals to report data to the network or receive updates from the network.
For MTC WTRUs that run on battery, such as sensors for use in remote maintenance, metering or monitoring, it is a major cost to exchange or charge the on-site batteries for a large amount of devices. Even for scenarios in which MTC WTRUs may consume power from an external power supply, it may be desirable to consume less power for energy efficiency purposes. Discontinuous reception (DRX) is a well-established method which is standardized and implemented in 3rdGeneration Partnership Project (3GPP) communication systems for power conservation. A user equipment (UE) may exhibit DRX by switching off its receiver for certain periods during the monitoring of the incoming signals, such as paging signals, from the network. It is of course appreciated that the longer the DRX cycle, the greater the potential power consumption saving. In 3GPP Release-12 study on MTC and other mobile data applications communications enhancements, extended DRX (E-DRX) is one of the candidate solutions introduced to improve UE power consumption.
Such known E-DRX method may however exhibit limitations and disadvantages which can become more pronounced with MTC applications. Since MTC applications are not always time-tolerant, the use of a simple, regular, but relatively long DRX cycle may cause communication problems between the MTC application and the MTC application server due to the MTC WTRU not successfully receiving the paging signaling. Extending paging cycle to such a long value may also cause large delay for mobile terminated (MT) service, which means a MT call may be delayed for a long time or even lost. Therefore, there is a need for a method of managing DRX in a wireless communication system for enhancing power saving while reducing the likelihood of network signaling being missed or delayed.